10%

The thing that I wanted to know more about was the theory that 'people only use 10% of their brain.' As the book revealed on day one, that is a myth. It has been proven false, since in 1999, brain scans have shown that every part of our brains have at least some function, and are active, some, if not all the time. The obvious question then arises, how much of our brain potential do we use? Every piece of the brain has a function, and if that part breaks down, small behavioral shifts (if not larger) will be present. I believe that this concept is important because it is a common misconception, as well as a mystery. Nobody can quite pin down a tangible number or percentage of how much of our capacity we use. In addition to that, going into this class, just a month ago, I would have believed that myth as well. The consensus seems to be that we use all parts, just not to their full capacity.
http://health.howstuffworks.com/human-body/systems/nervous-system/10-brain-myths10.htm
The link above provides information on the origin of the myth. In the words of William James "the average person rarely achieves but a small portion of his or her potential." In addition recent studies have concluded that we use even more than 10% while sleeping. In fact, authors and ESP enthusiasts have made extraordinary claims (without extraordinary evidence) that the mind has untapped functions that allow us to see the future, or read minds. Many books have been published regarding what the dormant 90% does that we don't even know about. The world needs to be set straight.